U.S. Pat. No. 6,783,326 (Aug. 31, 2004), which the instant application incorporates by reference, broadly discusses two significant uses of a panel bed of granular material: (1) for filtering a dusty gas, the filtration being assisted by an accumulation of dust deposits (filter cakes) upon fluid-entry faces of the granular material; (2) for countercurrent contacting of the granular material with a gas. See “Granular-bed filtration assisted by filter-cake formation: 1. Exploiting a new form of soil failure for renewal of filtration surfaces in a panel bed,” K.-C. Lee, R. Pfeffer, A. M. Squires, Powder Technology, vol. 155, 5-16, 2005; “2, The panel bed gas filter with puffback renewal of gas-entry surface,” I. Rodon, K.-C. Lee, A. M. Squires, O. K. Sonju, Powder Technology, vol. 155, 52-61, 2005; and “4. Advanced designs for panel-bed filtration and gas treating,” A. M. Squires, Powder Technology, vol. 155, 74-84, 2005. The referenced patent discloses means for renewing gas-entry faces of a panel bed of a granular material in which vertically disposed louvers (resembling slats of a Venetian blind) support the material: i.e., to provide a “reverse” surge flow of gas toward the gas-entry faces (a “puffback”). This surge flow produces a body movement of the granular material toward the faces, spilling moieties of the material from the faces and concomitantly exposing previously underlying material, thereby renewing the faces.
U.S. Pat. No. 4,000,066 (Dec. 28, 1976) broadly discusses two additional significant uses of a panel bed of granular material: (1) for filtering powdery matter from a liquid, the filtration being assisted by an accumulation of powdery matter deposits (filter cakes) upon liquid-entry faces of the granular material; (2) for countercurrent contacting of the granular material with a liquid. See “Granular-bed filtration assisted by filter-cake formation: 5. Treating a liquid in a panel bed with pulseback renewal of liquid-entry granular-bed faces,” J.-S. Yang, D. R. Whitmire, A. M. Squires, Powder Technology, vol. 155, 134-138, 2005. The referenced patent discloses means for renewing liquid-entry faces of a panel bed of a granular material in which vertically disposed louvers (resembling slats of a Venetian blind) support the material: i.e., to provide a “reverse” surge flow of liquid toward the liquid-entry faces (a “pulseback”). This surge flow produces a body movement of the granular material toward the faces, spilling moieties of the material from the faces and concomitantly exposing previously underlying material, thereby renewing the faces.